With the development of the mobile communication industry and the continuously increasing demand of mobile data services, people have increasingly higher requirements on the rate and Quality of Service (QoS) of the mobile communication, thus, before the 3rd Generation mobile communications (3G) is not used in large-scale commerce yet, the research and development work on the next generation mobile communication system has already been started, wherein the LTE project initiated by the 3rd Generation Partnership Project (3GPP) is more typical, and the maximum spectral bandwidth that can be provided by the LTE system is 20 MegaHert (MHz). With the further evolution of the network, the LTE-Advanced (LTE-A) system, as an advanced system of the LTE system, can provide the spectral bandwidth up to 100 MHz and support more flexible communication with higher quality, and meanwhile, the LTE-A system has good backward compatibility. Multiple Component Carriers (CC) exist in the LTE-A system, an LTE terminal can only work in a certain CC with backward compatibility, but an LTE-A terminal with stronger capability can perform transmission in multiple CCs simultaneously. That is, it is implemented that the LTE-A terminal transmitting and receiving data in multiple component carriers simultaneously, thereby achieving the object of promoting the bandwidth. The technology is called the multi-carrier aggregation technology.
The multi-carrier aggregation technology is supported in the LTE-A system, so as to achieve greater bandwidth through the multi-carrier aggregation for transmitting the data. The maximum number of carriers subordinate to the base station is 5, and these carriers are called component carriers, and all of them are carriers with backward compatibility, so as to support the User Equipment (UE) of the earlier LTE version to work. The base station can configure multiple component carriers for one UE and select part or all of the component carriers to be activated for the UE, thus the activated component carriers can provide data transmission for the UE.
In the study of the current stage, based on the multi-carrier aggregation technology, new requirements are raised with respect to aspects such as spectrum resource utilization rate, network energy saving and interference suppression between cells at the LTE R11 stage. In order to achieve this object, a new carrier type is put forward at present, and it is applied with the assistance of the carrier aggregation technology, and the new carrier has a distinct characteristic that it is not required to consider the backward compatibility in design, and more new technologies can be applied in the new carrier. For example, at present, in the LTE R11, with regard to the definition of the new carrier, it is required to be applied matching with at least one compatible carrier, and Cell-specific Reference Signals (CRS) of the LTE R8 are not configured in the new carrier, so as to avoid serious CRS interference at the edge of cell from the adjacent cell, especially the CRS interference between a macrocell and a microcell in a Heterogeneous Network (HetNet) scenario.
In the LTE Rel-8, a rule for sending Primary Synchronization Signals/Secondary Synchronization Signals (PSS/SSS) is that: in Frequency Division Duplexing (FDD), a position for sending the PSS/SSS is: a frequency domain, located at the intermediate 6 Physical Resource Block (PRB) pairs (a PRB is 12 subcarriers) of the system bandwidth, and a schematic diagram of the PRB, PRB pair and slot is given in the reference FIG. 1; and a time domain, located in the last 2 Orthogonal Frequency Division Multiplexing (OFDM) symbols of the first slots of the subframe #0 and subframe #5; in Time Division Duplexing (TDD), a position for sending the PSS/SSS is as shown in FIG. 2, including: a frequency domain, located at the intermediate 6 PRB pairs of the system bandwidth, and a time domain, wherein the PSS are located in the third OFDM symbols of the subframe #1 and subframe #6, and the SSS are located in the last OFDM symbols of the subframe #0 and subframe #5. In the LTE Rel-10, in order to promote the performance of reference signals, Demodulation Reference Signals (DMRS) based on the UE are introduced, and the DMRS are reference signals used for demodulation. In the subframes, the OFDM in which mapping patterns of the DMRS (referring to UE-specific reference signals used for demodulation in the LTE) (the patterns of the UE-specific reference signals related in the examples of the present document are subject to the 36.211v40) are located conflicts with the OFDM bearing the PSS/SSS in the intermediate 6 PRB pairs of the system bandwidth. In the LTE Rel-10, through the provision, the above problem is solved by not configuring to send the DMRS in the PRB pairs in which the DMRS conflict with the PSS/SSS, and since the CRS exist in the LTE Rel-10, the UE still uses the CRS to perform demodulation in these conflicting PRB pairs. In the above analysis, the number of subframes involved in conflict of the TDD is 2 or 4 (it depends on the uplink and downlink subframe configuration in the TDD mode), thus the confronting problem is more severe.
The PRB contains 12 subcarriers in the frequency domain, and it contains 6 correspondingly long Cyclic Prefixs (CP) and/or 7 correspondingly short CPs and OFDM symbols in the time domain, and the PRB pair contains identical subcarriers in the frequency domain, and it contains two continuous PRBs within one subframe in the time domain. One subframe is divided into 2 slots, and the former slot and the later slot are equilong. More detailed information may refer to the provisions of the LTE 36.211 protocol, and definitions of the 36.211 are completely adopted in the technical scheme of the present document.
In the LTE Rel-11, in order to achieve the object of further promoting spectrum efficiency, reducing interference from adjacent cells and implementing energy saving, the above carrier type is put forward, and it is called the new carrier here. At present, it is clear that the CRS are not sent in the new carrier, and reference signals which may be further sent are DMRS, Channel-State Information Reference Signals (CSI-RS) and reference signals used for synchronization tracking, and it is specified that the new carrier uses more efficient DMRS to perform demodulation, and mapping patterns of the CSI-RS within the subframes are subject to the provisions of the 36.211v40 (the patterns of the CSI-RS related in the examples of the present document are subject to the 36.211v40). Therefore, through the analysis, if it continues to perform the mapping of the DMRS in the way of the LTE Rel-10, there will be no reference signals used for demodulation in the intermediate 6 PRB pairs of the system bandwidth in the new carrier, and the problem that data cannot be transmitted exists in these 6 PRB pairs. If a new mapping rule is adopted for the mapping of the DMRS and the resource conflict between the DMRS and the PSS/SSS is avoided, it is also a method for solving the problem, but the design of the reference signals needs a great deal of simulation assessment support, and the amount of standardized works is very large. Moreover, another problem also exists in the new carrier, since it is not configured to send information including system information and paging information and so on in the new carrier, and the PSS/SSS continue to use sequences of the LTE Rel-8 in the new carrier, if the new carrier continues to send the PSS/SSS, a UE previous to the LTE Rel-11 will also detect the PSS/SSS sent in the new carrier, thus it makes the UE previous to the LTE Rel-11 incorrectly access the new carrier, and as the system information and so on are not sent in the new carrier, it makes the UE fail to work.